ME and CFS Definitions

Dr. Melvin Ramsay, who was one of the first people to study M.E. in an in-depth way.

Over the years, a number of case definitions for ME (myalgic encephalomyelitis) and CFS (chronic fatigue syndrome) have been put forth by various individuals and committees. These have varied considerably, creating great confusion with regard in the minds of physicians, researchers, media, government and patients.

Following is a brief discussion of some of these definitions.

IOM Definition for ME/CFS (2015)

In 2014, the U.S. Department of Health and Human Services commissioned a non-profit consulting company, the Institute of Medicine, to create a new clinical definition for the disease entity that it had previously been calling chronic fatigue syndrome.

The IOM has since changed its name to the National Academy of Medicine (NAM).

in early 2015, the committee put forth a set of criteria that it proposed as a replacement for existing definitions of ME/CFS for clinical purposes. Unlike previous definitions, the IOM/NAM criteria suggested a very streamlined diagnostic approach looking only at five illness symptoms (reduced activity level, post-exertional malaise, unrefreshing sleep, cognitive impairment and orthostatic intolerance).

The IOM/NAM committee also recommended that an entirely new name – systemic exertion intolerance disease or SEID – be adopted to go along with the definition.

The name “SEID” was fairly emphatically rejected by those in the ME and CFS communities and has virtually never been used since the release of the report.

The IOM/NAM definition has prompted more mixed reviews, with some people praising its simplicity and others suggesting that it does not accurately identify the right population.

The IOM/NAM report is referred to on the current CDC website, with the suggestion that health care providers consider the definition proposed in the report when diagnosing the disease.

In 2011, a group of physicians and researchers specializing in ME and CFS released a consensus definition for ME, called the International Consensus Criteria.

This definition is particularly noteworthy because it focuses on more severe patients, with both a 50% or more reduction in activity and a wide variety of moderate or severe symptoms required to qualify.

The criteria are quite complex, including many different categories and with multiple symptoms from long lists in different categories required to qualify. Although many people like the idea of this definition (especially for research purposes) because of its focus on severe patients, it also has been criticized as being difficult for busy practitioners to actually use. It also has been said to be problematic for clinical purposes because it may fail to diagnose patients who are in the initial stages of the illness prior to becoming severely ill.

The definition requires that individuals must experience sleep dysfunction, pain, cognitive/neurological issues and post-exertional malaise, as well as some additional symptoms, in order to qualify for a diagnosis.

In 2005, the authors of the paper published a set of practitioner guidelines summarizing the information in the criteria.

In 2013, virtually all of the highest-profile clinicians and researchers specializing in the disease wrote a letter to the Secretary of the Department of Health and Human Services asking that this definition be adopted by the U.S. government.

Thus far, the CDC has continued to use and support the Fukuda definition, however.

In 1994, a group of researchers associated with government agencies in the U.S., the U.K. and Australia released a new definition for chronic fatigue syndrome (CFS). The definition was stated as being designed to replace the CDC Holmes Criteria, which had been released in 1988.

The definition has often been criticized due to the fact that patients can qualify for it even if they do not experience any exercise intolerance and for its general focus on fatigue rather than other symptoms that M.E. patients tend to find more problematic.

The criteria include the experience of extended substantial fatigue, plus four out of eight symptoms listed.

This definition remains the main one referenced on the CDC’s website and is the basis for most of the research that has been done on ME or CFS patients thus far.

This definition for “chronic fatigue syndrome” was developed by a group of psychiatrists in the UK in 1991.

The only criterion for qualification for the diagnosis is unexplained fatigue that continues for six months or more, with a few specific diseases excluded. Because this definition looks only at fatigue (and because it does not exclude those with depression), it points to a different group of patients than the other definitions listed on this page.

The Oxford definition was used to select patients for the controversial PACE Study and the other research studies published by this group of UK psychiatrists. The use of this definition has been cited as a key problem by investigative journalist David Tuller and others critical of these psychiatrists’ work.

In 2014, the U.S. National Institutes of Health sponsored a panel discussion with the goal of getting input on moving forward with research for what it had begun calling “ME/CFS.” The report produced by the panel was called “Pathways to Prevention Workshop: Advancing the Research on ME/CFS.” With regard to the Oxford Criteria, the panel stated:

Furthermore, the multiple case definitions for ME/CFS have hindered progress. Specifically, continuing to use the Oxford definition may impair progress and cause harm. Thus, for needed progress to occur we recommend (1) that the Oxford definition be retired, (2) that the ME/CFS community agree on a single case definition (even if it is not perfect), and (3) that patients, clinicians and researchers agree on a definition for meaningful recovery.

The Holmes Criteria were developed in 1988 by a committee of physicians – including the two CDC doctors who investigated the Tahoe outbreak – subsequent to a large amount of media coverage of the Lake Tahoe epidemic. It was stated as being a working definition so that researchers would be able to appropriately study the disease.

Specific mention was made of “the chronic fatigue syndrome” being a replacement for the previous concept of “chronic Epstein-Barr virus,” which had been the subject of several research papers. The established disease of myalgic encephalomyelitis was not discussed in the article.

The criteria included ongoing fatigue resulting in a reduction of activity of at least 50% as well as the presence of at least eight out of a list of 14 symptoms. A large number of other conditions were stated as exclusionary.

The Ramsay criteria were developed by Dr. Melvin Ramsay, a UK physician who was involved in studying the illness outbreak at the Royal Free Hospital in London in 1955. He devoted the remainder of his life until his death in 1990 to studying the disease.

Dr. Ramsay wrote a number of articles and books on the disease, including descriptions of the characteristics that he felt were most typical of it.

The description of M.E. from 1988 suggests an illness that often has an acute onset and that then becomes chronic. He suggests that three major groups of symptoms are present in the chronic condition – muscle impairment, circulatory impairment, and cerebral dysfunction. A number of other symptoms usually are present as well, he stated.

Although the Ramsay Criteria rarely have been used in the U.S. for research purposes or for official diagnoses, many physicians have stated that the criteria have been useful in allowing them to quickly recognize the illness in their practices.

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